The work in progress in our laboratory is concerned with (1) the biochemical mechanisms underlying adhesive recognition among embryonic cells, and (2) the role of cell surface glycosyltransferases in polysaccharide biosynthesis and cell migration. For the first objective, we utilize an in vitro assay for retinotectal specificity between chick embryo retinal cells and tectal hemispheres. Enzymatic dissection of cell surface components has led to the conclusion that the Tay-Sachs ganglioside is a recognition molecule in this system. In current work, this conclusion is being tested by adding oligosaccharide chains isolated from various gangliosides to the in vitro assay. An antiserum against the Tay-Sachs ganglioside has been purified on affinity columns and is also being used in the recognition assay. The second objective is being met by a multi-faceted approach to the glycosyltransferases of the chick embryo. We are investigating the glucoronyltransferases of the developing liver. These enzymes have many specificities, are all membrane-bound, and are rapidly inducible by treatment, of the early chick embryo with phenobarbital. We are also using specific, transferase inhibitors to perturb in vivo and in vitro morphogenesis as represented by early embryos and by normal and transformed cells in culture.